We propose to develop and evaluate an alternative method for selecting and manipulating objects in a graphical user interface (GUI) based on circling the target rather than pointing and clicking. Some individuals with disabilities find it difficult or impossible to consistently and efficiently perform operations involving the left and right mouse buttons (e.g., left clicking to select an item or activate a button, right clicking to display a context menu, double-clicking an icon to launch an application, clicking-and-dragging to move an icon or select text). Several alternatives to the left and right buttons on traditional computer mice already exist, including interfaces for adaptive switches and dwell-clicking software, but each approach has its own limitations and trade-offs. Potential advantages of a circling interface include: 7 No need to operate physical buttons or switches; 7 No need to keep the cursor positioned over a target long enough to use dwell-clicking; 7 Compatible with many types of pointing devices. We will establish an advisory board of eight individuals with disabilities who are potential users of the proposed software. Advisory board members will be recruited from the consumers at United Cerebral Palsy of Pittsburgh and Three Rivers Center for Independent Living who have met with Dr. Simpson in the past regarding their computer access needs. We will recruit members with a range of disabilities, including cerebral palsy, spinal cord injury, Parkinson's disease, amyotrophic lateral sclerosis, and multiple sclerosis. We will implement testbed software that allows us to present a variety of realistic pointing tasks which can be completed by circling the target with the mouse cursor, pressing a mouse button, or using dwell-click software. The advisory board will meet every month for the first nine months of the project to review the software. In between meetings, revisions to the software will be posted on a project website. The advisory board will provide feedback regarding all aspects of the software's design. Once the software is completed, we will compare the performance of individuals with disabilities on pointing tasks with a circling interface to performance on the same tasks when using the left and right buttons and with dwell-clicking software. We will test the hypothesis that users with disabilities can perform the target of pointing operations more quickly and accurately with a circling interface than with physical mouse buttons or dwell-clicking software. The proposed research is expected to result in a novel method for selecting and manipulating objects within graphical user interfaces, and is expected to be useful for both computer access and augmentative communication software. For some individuals with disabilities, a circling interface will be more efficient and accurate than alternatives based on switches or dwell-clicking and will make computers and augmentative communication devices easier to use. The proposed circling interface will be relatively easy to integrate into new and existing products, increasing the likelihood of commercial adoption.